1. Field of the Invention
Exemplary embodiments relate to a proximity measurement method and apparatus for device-to-device (D2D) communication in a mobile communication system to measure proximity for direct communication between devices in the mobile communication system.
2. Description of the Related Art
Recently, with the spread of smart phones and the like, an amount of wireless data usage in a mobile communication system is greatly increasing and an amount of data exchange between mobile terminals is also increasing due to social network applications and the like. To handle the considerably increasing traffic of a mobile communication network, a method of improving a wireless transmission rate, a method of using a radio resource effectively using a small cell such as a femto cell in a macro cell, and the like, are being applied.
However, in a case in which a small cell is used, costs for handling traffic in a mobile communication core network increase greatly due to sharply increasing traffic since a small cell has a structure of accessing a mobile communication core network, and costs for managing a large number of small cells in a mobile communication core network also increase. Accordingly, active studies have been conducted on a wireless backhaul to reduce costs for maintaining and managing small cells, however due to characteristics of a wireless backhaul, high speed packet transmission may cause an issue.
One of the features of resulting traffic with the advent of a social network service is regionality involved in user meetings, for example, friendship, coworkership, and the like. Regionality-based traffic is transmitted via a gateway of a mobile communication core network due to characteristics of mobile communication, and this traffic causes a high load on a transport network between a mobile communication core network and a base station.
An existing traffic handling method in a mobile communication network is incapable of distinguishing regionality-based traffic, and on this account, research has been conducted on methods for handling regionality-based traffic. Recently, as one of the solutions of handling regionality-based traffic, technologies for device-to-device (D2D) communication are being studied.
As one of the technologies for D2D communication, reference may be made to Korean Patent Publication No. 10-2012-0100833, published on Sep. 12, 2012, titled “method of performing direct communication between terminals and terminal for supporting the same” in which a resource is commonly allocated to all cells and D2D communication is performed between a first terminal and a second terminal using the common D2D communication resource having fixed size and location.
To enable D2D communication, a process for measuring proximity is required to determine whether devices being communicating with one another are capable of D2D communication, and may be classified into a method of measuring proximity in response to a request from an application program and a method of measuring proximity automatically by internal processing of a mobile communication network. However, packet traffic in a mobile communication network is not managed by independent sessions for each service but is handled by one integrated session within which a plurality of services are used, and for this reason, it is difficult to recognize triggers for D2D communication between mobile communication terminals. To solve this issue, packets routed on a gateway may be all examined at the gateway, however a high load may be applied to the gateway, resulting in reduced efficiency.
Accordingly, there is a demand for a method of measuring proximity between devices without applying a change or load to packet routing and a control protocol of an existing mobile communication core network.